Metamaterials are typically artificially structured composite materials. Components and structural parameters may be selected to obtain electromagnetic properties that are not readily available in a homogeneous material.
The electromagnetic response of metamaterials is discussed in Int. Pub. WO 2006/023195 to Smith et al. In some metamaterial examples, permittivity and/or permeability may be negative at the electromagnetic frequency of interest. A metamaterial typically comprises a plurality of unit cells. In typical examples, each unit cell includes an electrically conducting pattern, such as a resonator, for example a split ring resonator, supported on a dielectric substrate. The metamaterial response may be determined from the unit cell parameters. Unit cell parameters include parameters such as resonant frequency.
However, the range of unit cell parameters available may have an effective upper and lower bound, for example due to manufacturing limitations such as physical limits on a size variation. Such limitations conventionally present a restriction on the index variation possible within a metamaterial, and limit applications of a metamaterial.